The foster mom did what came naturally when her new child had a birthday: She baked her a chocolate cake.

When the girl came home from school and saw the cake, she burst into tears. The foster mom said she was sorry for upsetting her and explained she'd meant to make her happy. She offered to bake a different cake, if the girl didn't like chocolate.

"It's not that," she replied. "I've just never had a birthday cake."

Libby Gruender of Sunnyvale read about that incident in 2010 and pledged to provide birthday cakes for children in foster care so they would each feel loved on their special day. She founded Cake4Kids to carry out the mission.

Gruender died in 2013 but her commitment lives on, and Cake4Kids has expanded. Today 400 volunteer bakers across the Bay Area, including 20 in Pleasanton, produce 1,800 cakes a year working with more than 65 agencies.

"Now we also deal with low income, homeless shelters, domestic violence agencies, human trafficking agencies," executive director Julie Eades said. "We help mothers who are getting back on their feet -- a lot of people are looking after the mothers, and the children kind of get on with their lives."

"These kids often live in hand-me-downs, they often don't get anything of their own," she said. "Some are moved from group home to group home, and birthday cakes are not considered an essential of life."

Cake4Kids recently provided the first birthday cake for a 20-year-old man who had spent his life in group homes.

"It is like a moment in time when people sing to you in front of your cake," Eades said.

"The cakes are all home-baked," she added. "When someone bakes a cake for another person, it is baked with a certain amount of love."

Of course, with so many cakes there are bound to be a few emergencies -- such as a dropped cake -- when someone has to dash into a bakery, she added with a laugh.

"We have all sorts of cake dramas," she noted.

Each cake has the child's name on it and is created according to his or her tastes or interests. A child might make a request, or a social worker will come up with an idea to personalize it.

"It helps with their self-esteem," Eades said. "Some ask for cupcakes and they take some to school to share."

Some of the bakers have nut-free kitchens so they take the requests from those dealing with allergies.

"A lot of our bakers get a lot of joy out of this," Eades said. "It is wonderful to combine people who love to bake with children."

Pleasanton has 20 volunteer bakers, Danville has 25 and San Ramon has eight, according to the last report, in February.

"We are always looking for baker volunteers in Alameda and Contra Costa," Eades said. "You have to be at least 16." Visit the Cake4Kids website for more information.

"If there are any companies in the Tri-Valley area that encourage their employees to volunteer and have volunteer days or would like to host us on-site to talk about what we do, we'd love to do that," she added.

"The bakers never get to see the children. The agency gets the cake to the child," Eades said. "Sometimes these case workers don't always have the easiest relationships with the children -- they have been moved around and disappointed in life. I have heard stories where a social worker says she now has such a better relationship with a child."

The group works as far south as Gilroy. It opened in San Francisco last summer, just started in Marin County and has been requested in Solano County -- and in Fresno. The core group is developing software to help others get started.

"We might branch out and do chapters in the rest of California, and if that works out, we might take it to other states," Eades said.

Cake4Kids is mostly a volunteer organization but pays two part-time office staff members. It holds fundraisers to cover expenses, including an annual Cake-Off in the South Bay. Last month it held the first Cake-Off4Kids in the East Bay, at the Danville Community Center.

The Cake-Off had three categories: Best tasting, best decorated and best cake by someone under 15. The 23 contestants also brought a second cake, which they cut up and offered to the attendees. The fundraiser drew 115, with adults paying $30 to attend; children were $15. There was also a silent auction.

"With this first event, we just wanted to cover our costs but we did make some money," Eades said. "It was a fun family thing, only over a couple of hours. We also had a kids' activity area. We intend to be back next year for another one."

A fundraising Cake4Kids Celebration Dinner on Oct. 27 in Palo Alto will have a three-course dinner, wine, drawings and a live auction. Tickets are $150. Information will soon be published at Cake4Kids.org.

The group is funded mainly by donations from individuals, Eades said, and a lot of people find it on the internet.

"A woman whose mother had died contacted us," she said. "Her mother had been a foster child way back when, and she was looking to do something in lieu of flowers and said they'd like donations to go to our organization."

The entries at the Cake-Off4Kids were amazing, Eades said, but so are all the cakes made by the volunteer bakers.

She recalled a 12-year-old boy last year living in a shelter with his mother who worked three jobs to afford the rent. She asked the social worker for a "Frank Sinatra cake" because the boy's grandfather, who had died, used to play Sinatra records for him.

"One of our bakers picked up the request, put on a picture of Frank Sinatra, the boy's name, and the words, 'May you live to be 100,'" Eades remembered. "He said, 'I cried when I opened the box.' He thought it was the best thing ever."